Are cell phone services readily available in your location? What are the preferred vendors?
Yes. There are only 3 mobile operators in Slovakia: T-Mobile, Orange and Telefonica (O2)
What is the usual process to obtain this service?
Just signing the contract or buying the cell phone and prepaid credit for calling. For those transferees who do not have residency in the Slovak republic only rechargeable service is available, for those that have necessary registration it is possible to sign the contract for the regular invoiced services.
Is it legal for a third party to set up services?
Contract must be signed in person, prepaid credit can be bought by anybody.